// FILE: ./internal/sources/openmeteo/observation.go
package openmeteo

import (
	"context"
	"encoding/json"
	"time"

	"gitea.maximumdirect.net/ejr/feedkit/config"
	"gitea.maximumdirect.net/ejr/feedkit/event"
	"gitea.maximumdirect.net/ejr/weatherfeeder/internal/providers/openmeteo"
	"gitea.maximumdirect.net/ejr/weatherfeeder/internal/sources/common"
	"gitea.maximumdirect.net/ejr/weatherfeeder/internal/standards"
)

// ObservationSource polls an Open-Meteo endpoint and emits one RAW Observation Event.
type ObservationSource struct {
	http *common.HTTPSource
}

func NewObservationSource(cfg config.SourceConfig) (*ObservationSource, error) {
	const driver = "openmeteo_observation"

	hs, err := common.NewHTTPSource(driver, cfg, "application/json")
	if err != nil {
		return nil, err
	}

	return &ObservationSource{http: hs}, nil
}

func (s *ObservationSource) Name() string { return s.http.Name }

func (s *ObservationSource) Kind() event.Kind { return event.Kind("observation") }

func (s *ObservationSource) Poll(ctx context.Context) ([]event.Event, error) {
	raw, meta, err := s.fetchRaw(ctx)
	if err != nil {
		return nil, err
	}

	var effectiveAt *time.Time
	if !meta.ParsedTimestamp.IsZero() {
		t := meta.ParsedTimestamp.UTC()
		effectiveAt = &t
	}

	emittedAt := time.Now().UTC()
	eventID := common.ChooseEventID("", s.http.Name, effectiveAt, emittedAt)

	return common.SingleRawEvent(
		s.Kind(),
		s.http.Name,
		standards.SchemaRawOpenMeteoCurrentV1,
		eventID,
		emittedAt,
		effectiveAt,
		raw,
	)
}

// ---- RAW fetch + minimal metadata decode ----

type openMeteoMeta struct {
	Timezone         string `json:"timezone"`
	UTCOffsetSeconds int    `json:"utc_offset_seconds"`

	Current struct {
		Time string `json:"time"`
	} `json:"current"`

	ParsedTimestamp time.Time `json:"-"`
}

func (s *ObservationSource) fetchRaw(ctx context.Context) (json.RawMessage, openMeteoMeta, error) {
	raw, err := s.http.FetchJSON(ctx)
	if err != nil {
		return nil, openMeteoMeta{}, err
	}

	var meta openMeteoMeta
	if err := json.Unmarshal(raw, &meta); err != nil {
		// If metadata decode fails, still return raw; envelope will omit EffectiveAt.
		return raw, openMeteoMeta{}, nil
	}

	if t, err := openmeteo.ParseTime(meta.Current.Time, meta.Timezone, meta.UTCOffsetSeconds); err == nil {
		meta.ParsedTimestamp = t.UTC()
	}

	return raw, meta, nil
}